PMID- 34334194 OWN - NLM STAT- MEDLINE DCOM- 20210923 LR - 20210923 IS - 1525-3198 (Electronic) IS - 0022-0302 (Linking) VI - 104 IP - 10 DP - 2021 Oct TI - Expression of specific signaling components related to muscle protein turnover and of branched-chain amino acid catabolic enzymes in muscle and adipose tissue of preterm and term calves. PG - 11291-11305 LID - S0022-0302(21)00762-1 [pii] LID - 10.3168/jds.2021-20527 [doi] AB - Postnatal metabolism depends on maturation of key metabolic pathways around birth. In this regard, endogenous glucose production is impaired in calves born preterm. Concerning protein metabolism, the rates of protein turnover are greater during the neonatal period than at any other period of postnatal life. The mammalian target of rapamycin (mTOR) and the ubiquitin-proteasome system (UPS) are considered as the major regulators of cellular protein turnover. The objectives of this study were to investigate (1) the changes in plasma AA profiles, (2) the mRNA abundance of mTOR signaling and UPS-related genes in skeletal muscle, and (3) the mRNA abundance of branched-chain AA (BCAA) catabolic enzymes in skeletal muscle and adipose tissue in neonatal calves with different degree of maturation during the transition to extrauterine life. Calves (n = 7/treatment) were born either preterm (PT; delivered by cesarean section 9 d before term) or at term (T; spontaneous vaginal delivery) and were left unfed for 1 d. Calves in treatment TC were also spontaneously born but were fed colostrum and transition milk for 4 d. Blood samples were collected from all calves at birth and at 24 h of life. Additional blood samples were taken 2 h after feeding (26 h of life) for PT and T calves, and on d 4 of life for TC, to determine plasma glucose, urea, and AA. Tissue samples from 3 muscles [M. longissimus dorsi (MLD), M. semitendinosus (MST), and M. masseter (MM)], and kidney fat were collected following euthanasia at 26 h after birth (PT, T) or on d 4 of life (TC) at 2 h after feeding. The concentrations of the majority of plasma AA (Ala, Gln, Asn, Cit, Lys, Orn, Thr, and Tyr), nonessential AA, and total AA were greater during the first 24 h and also before and 2 h after feeding in PT than in T. The ratio of plasma BCAA to the aromatic AA (Tyr and Phe) was greatest in TC, followed by T, and least in PT. The mRNA abundance of mTOR and ribosomal protein S6 kinase 1 (S6K1) in MLD and MM was greater in PT and T than in TC. The mRNA abundance of muscle-specific ligases FBXO32 (F-box only protein 32) in the 3 different skeletal muscles and TRIM63 (tripartite motif containing 63) in MLD was greater in PT and T than in TC; in MM, TRIM63 mRNA was greatest in PT. The mRNA for BCKDHA and BCKDHB (the alpha and beta polypeptide of branched-chain alpha-keto acid dehydrogenase) in kidney fat was elevated in PT and T compared with TC, suggesting a possible enhancement of BCAA oxidation as energy source to cover the energetic and nutritional postnatal demands in PT and T in a starved state. The increased abundances of mTOR-associated signaling factors and muscle-specific ligase mRNA indicate a greater rate of protein turnover in muscles of PT and T in a starved state. Elevated plasma concentrations of several AA may result from enhanced muscle proteolysis and impaired conversion to glucose in the liver of PT calves. CI - Copyright (c) 2021 American Dairy Science Association. Published by Elsevier Inc. All rights reserved. FAU - Sadri, H AU - Sadri H AD - Department of Clinical Science, Faculty of Veterinary Medicine, University of Tabriz, 5166616471 Tabriz, Iran. FAU - Ghaffari, M H AU - Ghaffari MH AD - Institute of Animal Science, Physiology Unit, University of Bonn, 53111 Bonn, Germany. FAU - Steinhoff-Wagner, J AU - Steinhoff-Wagner J AD - Institute of Nutritional Physiology "Oskar Kellner," Leibniz Institute for Farm Animal Biology (FBN), 18196 Dummerstorf, Germany. FAU - Gors, S AU - Gors S AD - Institute of Nutritional Physiology "Oskar Kellner," Leibniz Institute for Farm Animal Biology (FBN), 18196 Dummerstorf, Germany. FAU - Hammon, H M AU - Hammon HM AD - Institute of Nutritional Physiology "Oskar Kellner," Leibniz Institute for Farm Animal Biology (FBN), 18196 Dummerstorf, Germany. FAU - Sauerwein, H AU - Sauerwein H AD - Institute of Animal Science, Physiology Unit, University of Bonn, 53111 Bonn, Germany. Electronic address: sauerwein@uni-bonn.de. LA - eng PT - Journal Article DEP - 20210730 PL - United States TA - J Dairy Sci JT - Journal of dairy science JID - 2985126R RN - 0 (Amino Acids, Branched-Chain) RN - 0 (Muscle Proteins) SB - IM MH - Adipose Tissue/metabolism MH - Amino Acids, Branched-Chain/metabolism MH - Animals MH - Cattle MH - *Cesarean Section/veterinary MH - Diet MH - Female MH - *Muscle Proteins/metabolism MH - Muscle, Skeletal/metabolism MH - Pregnancy MH - Proteolysis OTO - NOTNLM OT - mammalian target of rapamycin OT - muscle OT - neonatal calf OT - premature OT - ubiquitin-proteasome system EDAT- 2021/08/03 06:00 MHDA- 2021/09/24 06:00 CRDT- 2021/08/02 05:32 PHST- 2021/03/26 00:00 [received] PHST- 2021/06/14 00:00 [accepted] PHST- 2021/08/03 06:00 [pubmed] PHST- 2021/09/24 06:00 [medline] PHST- 2021/08/02 05:32 [entrez] AID - S0022-0302(21)00762-1 [pii] AID - 10.3168/jds.2021-20527 [doi] PST - ppublish SO - J Dairy Sci. 2021 Oct;104(10):11291-11305. doi: 10.3168/jds.2021-20527. Epub 2021 Jul 30.